1. Field
The embodiments of this document are directed to a navigation system, and more specifically to a map matching apparatus and method for performing map matching on a GPS receipt location.
2. Related Art
In general, navigation systems provide information helpful for driving a vehicle using a satellite.
A navigation system includes a GPS (global positioning system) module that receives a GPS signal from a GPS satellite and calculates a location of a vehicle based on the GPS signal.
The navigation system provides map data in which GPS receipt locations are map-matched to roads and guides a path requested by a user using the map data. The map data includes line data having a number of interpolation points (hereinafter, also referred to as “linear data”). For the conventional GPS systems, a map matching scheme is used that matches GPS receipt locations to the linear data.
FIG. 1 is a view illustrating a method of map-matching GPS receipt locations to the linear data.
Referring to FIG. 1, a GPS receipt location 101 may have a distance error amounting to a few tens of meters due to characteristics of the GPS signal, and often departs from a road.
The navigation system forces the GPS receipt location 101 to match a location 105 corresponding to a road 103 that is located closest to the GPS receipt location 101 and puts a mark at the location 105 to indicate the location of the vehicle.
FIG. 2 is a view illustrating data for displaying linear data. Referring to FIG. 2, to provide the linear data 201 as a map image, the linear data 201 is transformed to planar data which is represented as a plane in consideration to a width W of the road.
The planar data 202 may provide a more realistic map image rather than the linear data 201. However, while the map image uses the planar data 202, the GPS receipt location is subjected to map matching based on the linear data 201. Accordingly, the mark 203 ends up being positioned at a center or central line of the road. Thus, it is required to enhance such a map matching scheme.
The navigation system may differentially constitute linear data for each lane and performs mapping of the GPS receipt locations considering the linear data for each lane. However, when the linear data is not differentiated for each lane, an error may occur at a broad road or toll gate to match the GPS receipt locations to other adjacent roads.
For purposes of illustration, as shown in FIG. 3, a highway 301 having a broad width W1 and a road 302 having a narrow width W2 are adjacent to each other and a vehicle drives on the highway 301. The navigation system calibrates the GPS receipt location 305 to linear data of a road closest to the GPS receipt location 305 among roads around the GPS receipt location 305.
However, when a distance d2 between the GPS receipt location 305 and the linear data 304 for the road 302 is closer to a distance d1 between the GPS receipt location 305 and the linear data 303 for the highway 301, although the vehicle travels on the highway 301 and the GPS receipt location 305 is located within the width W1 of the highway 301, an error may occur that matches the GPS receipt location 305 to the road 302.
Such a map matching error causes it difficult to perform a normal path guidance and deteriorates users' reliability. Accordingly, there is a need for an enhanced map matching scheme that fits a navigation system with high GPS receipt and displaying performance.